Rotary Filter Apparatus For Roll-To-Roll Nanomaterial Dispersion Papermaking

ABSTRACT

An apparatus for roll-to-roll nanomaterial dispersion papermaking includes a suction pressure for consolidating nanomaterials on a fluid permeable filter in one region of the filter and an opposite pressure region or regions for separating a mat of the consolidated nanomaterials and transferring the mat to a transfer roller. A transfer roller may have a suction pressure within the transfer roller to help transfer the mat from the filter to the transfer roller, for example. An inlet port distributes nanomaterials using row and zone inlets, for example.

CROSS-RELATED INVENTIONS

This application is a 371 U.S. national phase application ofInternational Application PCT/US2017/056636 filed Oct. 13, 2017 whichclaims the benefit of the filing date of U.S. Provisional No.62/408,434, which was filed on Oct. 14, 2016, which is incorporated byreference herein in its entirety.

FIELD OF THE INVENTION

The field relates to papermaking, especially “bucky paper” made ofnanostructures, such as nanotubes, or other nanomaterials.

BACKGROUND

U.S. Pat. No. 7,459,121 discloses a known method for continuousproduction of a nanotube mat. However, the disclosed apparatus andmethod has difficulty in removing the mat from the drum without damagingthe mat, such as by tearing or buckling the mat. U.S. Pat. Publ. No.2011/0111279 discloses a binder-free nanocomposite material usingnanotubes, such as carbon nanotubes. The publication discloses a methodof suspending nanotubes using sonication and surfactants or othermethods. A flow cell sonication process is disclosed, in particular,with additional particles added to create a stable or semi-stablesuspension. The references disclose that a mat is made by filtering thesuspension through a microporous membrane. The publication disclosesusing several suspensions to provide a layer-by-layer compositestructure. However, this publication does not disclose a process thatcan produce continuous mats or that can alter the composition of the matin other ways. Instead, the process is a batch process for formingsheets.

U.S. Pat. Publ. No. 2013/0270180 discloses a process for producing acontinuous membrane including nanowires. The process uses a belt androllers similar to a process of papermaking with cellulose fibers calleddewatering. However, this publication discloses a “knife” (as used inapplying coatings) to spread and disperse a dispersion on a poroussubstrate surface or, in the alternative, the publication mentions, butdoes not disclose, the following processes: extrusion, slot coating,curtain coating or gravure coating processes that are, according to thereference, known in the art. The reference discloses known binders andconditioners, such as complexing agents and reactive bonding materials.This publication discloses the importance of a binder for making itsporous ceramic membranes using its particular chemistry to makeinorganic polymer-like crosslinking. While this publication discloses aprocess amendable to continuous fabrication of sheets, it fails todisclose any rotary drum or inlets capable of directing a suspensionand/or additives to change the composition of a continuous mat, locally.Instead, the entire ceramic thickness is dispensed from the knife (orother dispenser) at one time.

SUMMARY

A fluid suspension of nanomaterials is formed that disperses thenanomaterials, such as exfoliated graphene, graphene oxide platelets,single-walled and multi-walled nanotubes, nanofibers, micro- ornano-fibrillated cellulose, nanocrystalline cellulose, metal particles,quantum dots, ceramic particles, biomaterial particles, chitins, such aschitosan, nanowires, such as silicon, carbon, germanium and othernanowires, nanoclays, such as montmorillonite, bentonite, kaolinite,hectorite and halloysite, proteins, enzymes, antibodies, cellularmaterials, hemoglobin, DNA, RNA, liposomes, ribosomes, viruses,bacteria, marking and tagging agents, and combinations of thesethroughout the suspension while controlling agglomeration, ifagglomeration is allowed. Combinations and permutations of selectednanomaterials depend on each particular application and the type of“buckypaper” desired. In one example, nanomaterials comprise primarilynanotubes and materials for dispersing the nanotubes in a liquidsuspension and for binding the nanotubes after the nanotubes areconsolidated into a mat. For example, surfactants, solvents, monomersand polymers may be added to help prevent agglomeration ofnanomaterials. In one example, the nanotubes are carbon nanotubes, butother types of nanotubes may be used, such as carbon, boron, molybdenumand other elements capable of forming nanotubes, alone or as borides,nitrides, carbides or the like.

In one example, a batch process introduces the liquid suspension ofnanotubes into an apparatus comprising a rotary filter. Alternatively, acontinuous process introduces additional fluid suspension withadditional nanotubes as the process continues to deposit nanotubes onthe surface of the rotary filter. The rotary filter is rotated,mechanically or fluidically. Pores in the rotary filter allow fluid fromthe suspension to pass through the pores while at least some of thenanotubes suspended within the fluid collect on a surface of the rotaryfilter. Preferably, all of the nanomaterials are deposited onto therotary filter once a mat layer is formed on the rotary filter.

A nanotube mat is formed on the surface of the rotary filter, while thesurface of the rotary filter is rotated through the suspension. Thefluid is drawn through the pores by a pressure differential. Thepressure differential is established by a pump that draws the fluidthrough a portion of the rotary filter that is disposed in the fluidsuspension. As the fluid is drawn through the rotary filter, a mat ofnanotubes is formed on the surface of the filter, while the filtercontinues to rotate. As the portion of the filter rotates, the thicknessof the nanotube mat increases.

A block shields a portion of the rotary filter from the suction producedby the pump, when the portion of the filter with a nanotube mat reachesthe location of the block, the pressure difference decreases and fluidis not drawn through the portion of the filter shielded by the block orthe rate of fluid transfer is much less, if some pressure differentialstill draws some fluid through the mat and the rotary filter.

In one example, the block includes a backwash section that provides areverse pressure differential, causing fluid to pass from the backwashout through the rotary filter, rather than radially inwardly. Thisbackwash provides a force that separates the nanotube mat from thesurface of the rotary filter. In one example, a peeling roller isprovided that provides a pressure differential along an arcuate surfaceof the peeling roller, which provides a suction pressure that draws thenanotube mat onto the peeling roller. In one example, the peeling rollerhas another arcuate region where the pressure differential is reversed,and the nanotube mat is separated from the surface of the peelingroller. In one example, a transfer roller is arranged to apply atransfer film onto an exposed surface of the nanotube mat as the mat isin contact with the peeling roller. Then, the nanotube mat and thetransfer film, on one side of the mat, are directed to a reel and arewound onto the reel for transport and further processing, for example.

In one example, fluid is drawn by a pump through a port in fluidcommunication with the portion of the surface of the rotary filterpassing through the fluid suspension of nanotubes. For example, aportion of a cylindrical rotary filter that is shielded by a block maybe exposed to a lower pressure differential, no pressure differential ora reverse pressure differential. The reverse pressure differential maycontribute to separation of the nanotube mat from the surface of therotary filter, for example. In one example, separation is aided by apeeling roller that has a pressure differential that draws the nanotubemat onto the peeling roller.

Alternatively, the peeling roller may comprise a pair of rollers and abelt. The belt may be made of a porous material, such as a Teflon orother non-stick mesh that contacts the surface of the nanotube mat, suchthat suction through the mesh can help to peel the nanotube mesh fromthe rotary filter. In one example, a transfer film is applied to theexposed side of the nanotube mat at a second roller. For example, thesecond roller may have a reverse pressure differential that helps toseparate the transfer film and the nanotube mat from the belt, and themat and transfer film may be directed to a reel for transport and/orfurther processing.

In another example, instead of directing the nanotube mat to a transferfilm and a reel, the nanotube mat is separated from the rotary filterand is directed to a second rotary filter in a second fluid suspension.In one example, this may be repeated with subsequent suspensions orprocessing. In this way, the nanotube mat may be thickened,consolidated, functionalized or otherwise further processed. Eachsubsequent rotary filter or drum may use a suction pressure differentialto adhere the mat onto a roller, rotary filter or drum and/or reversepressure differential to peel the mat from a roller, rotary filter ordrum. Then, a transfer film and transfer roller may be used to transferthe processed mat to a reel for transport or further processing.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative examples and do not furtherlimit any claims that may eventually issue.

FIG. 1 illustrates an exploded view of an example of a rotary filterapparatus for roll-to-roll nanomaterial dispersion papermaking.

FIG. 2 illustrates a front view of the example shown in FIG. 1.

FIG. 3 illustrates a perspective view of the example shown in FIGS. 1and 2.

FIG. 4 illustrates a back view of the example shown in FIG. 2.

FIG. 5 illustrates a cross sectional view of the example shown in FIG.4.

FIG. 6 illustrates a detailed view of a portion of the example shown inFIG. 5.

FIG. 7 illustrates a schematic of an example of a rotary filterapparatus for roll-to-roll nanomaterial dispersion papermaking omittingdetails of the rotary drum apparatus for clarity.

FIG. 8 illustrates a schematic of another example of a rotary filterapparatus for roll-to-roll nanomaterial dispersion papermaking omittingdetails of the rotary drum apparatus for clarity.

FIG. 9 illustrates a schematic of yet another example of a rotary filterapparatus for roll-to-roll nanomaterial dispersion papermaking omittingdetails of the rotary drum apparatus for clarity.

FIG. 10 schematically illustrates an example of a rotary filterapparatus sourcing a plurality of sources (feedstock).

FIG. 11 schematically illustrates another example that controlsvalves/splitter (hubs) by computer.

FIG. 12 schematically illustrates a single line in and a single line outunder computer control (on-off only).

FIG. 13 schematically illustrates an on-off and mixing valve with twolines in and one line out.

FIG. 14 schematically illustrates an on-off and mixing valve with threelines in and one line out.

FIG. 15 schematically represents a cross section view of a couplingbetween a line and a port.

FIG. 16 schematically illustrates a single line coupled to a pair ofinlet ports (non-programmable splitter).

FIG. 17 schematically illustrates a simplified portion of a mat.

FIG. 18 illustrates inlet port zones associated with the mat of FIG. 17.

FIG. 19 illustrates a simplified cross section of a mat.

FIG. 20 schematically illustrates a mixing valve coupled to threedifferent sources.

FIG. 21 illustrates an example using a partially cut-away view showing aplurality of concave inlet rows, each a portion of an inlet, and showingone of a plurality of zones, each zone having a plurality of inlets, andeach of the zones being separated by dividers from each of the otherzones, which zones may be integrated into a barrier of the rotary filterapparatus.

When the same reference characters are used, these labels refer tosimilar parts in the examples illustrated in the drawings.

DETAILED DESCRIPTION

The example of an apparatus 10 in FIG. 1 shows how rotary seals 12 areassembled with a rotary filter 14 within a housing 16 having a fluidport 23 fluidically coupled with a pump 30 that provides a suctionpressure differential along an arcuate region. The arcuate region may becomprised of a barrier 18 with a plurality of ports 28 that allow ananomaterial suspended in a fluid to pass through the ports 28,unobstructed. The rotary filter 14 is comprised of a material having aporous surface 24 that allows suspension fluid, such as a solvent, topass through but blocks at least some of the nanomaterials from passingthrough the porous surface 24. For example, the porous surface may becomprised of a porous polymer membrane, such as apolytetrafluoroethylene polymer, a nylon polymer or a combinationthereof. For example, the porous surface may be comprised of astructural mesh with a porous polymer membrane supported by the mesh,which may be a metal mesh, for example. The rotary seals seal the sidesof the filter, such that fluid passes through, and preferably notaround, the filter surface 24. The mechanism for rotating the rotaryfilter may comprise a mechanical or fluidic drive. For example, FIG. 1shows a drive gear 118 that engages gear teeth 34 on the circumferenceof the rotary filter 14, for example. This simplifies the mechanism forrotating the rotary filter, allowing the drive gear 118 to be disposedout of the suspension fluid. For example, a simple worm gear may be usedto cause the rotary filter to rotate, without the need for additionalseals. A block 11 has an arcuate upper surface 21 that extends above thefluid level in the housing 16 and a flat lower surface 27 that extendsbelow the fluid level in the housing 16. The arcuate upper surface 21 isinterrupted by a cylindrical cutaway 15 that provides a zone of reversepressure differential provided by fluid entering through the backwashinlet 13 from the pump 30, for example. Alternatively, the cutaway maybe other shapes than cylindrical, such as a slot, a wedge or the like.The cutaway 15 is sealed, likewise, by rotary seals 12, and provides apositive, separation pressure that assists the peeling roller 17 in theprocess of peeling a nanomaterial mat from the surface 24 of the rotaryfilter 14. FIG. 2 shows an example of how the drive gear 18 engages theteeth 34 of the rotary filter 14. In FIG. 3, the perspective view showshow the peeling roller 17 engages a mat on the surface 24 of the rotaryfilter 14, for example. FIG. 4 shows the back surface 26 of the housing16 showing the location of the fluid port 23 and the backwash port 13. Ahole 43 for the shaft of the peeling roller 17 is shown, also. The lineA-A identifies a cross sectional view of the apparatus 10 that is shownin FIG. 5. A detailed view of a portion of the cross sectional view ofFIG. 5 is shown in FIG. 6 and represents the portion circled in FIG. 5.In FIG. 6, for example, a cross sectional view of the rotary filter 14is shown that illustrates in detail how the rotary seals 12 seal the lowpressure side of the apparatus 10 from the comparatively higher pressureside, which may be greater than 1 atm by introducing a pressurized gas,such as nitrogen or air, above the volume of liquid, using a pump 32 topump air into the high pressure side through high pressure inlet 31, forexample. Alternatively, the higher pressure side may be standardatmospheric pressure and whatever pressure is introduced by the fluid,itself, and the low pressure side may be less than 1 atm, drawing theliquid through the rotary filter, using the fluid suction pump 30, forexample.

In one example, a suspension inlet port 33 is used to introduce newsuspension fluid into the fluid volume of the apparatus, using asuspension pump 35, which pumps fluid suspension into the liquid volumeat a pressure greater than the pressure of the combined fluid head andthe pressure of any gas introduced by the high pressure pump 32.

In addition to port 33 or alternatively to port 33, ports 28 may directfluid directly through the barrier 18. In this example, the ports 28 maybe selected such that the ports 28 do not obstruct the flow of thenanomaterials suspended in the fluid from reaching the surface 24 of therotary filter 14, for example. In this example, the seal keeps fluidwithin the barrier 18, and ports 28 may be connected by tubes or linesto a distribution hub, such as a splitter, which directs a certainamount of the suspension to each of the ports 28. The pump directs fluidand nanomaterials through the tubes or lines to exit from the ports 28.In one example, there may be a plurality of ports coupled withreservoirs or sources of more than one type of suspension, which mayallow for an engineered deposition of nanomaterials and additives ontothe surface 24. In this way, the engineered “buckypaper” may havechannels and vias manufactured into the mat during the depositionprocess that forms the mat. For example, two different nanomaterialsuspensions may be pumped by two different pumps through two differentsonicators. A distribution hub may direct the two different nanomaterialsuspension to a plurality of different ports 28, depending on where thenanomaterials are to be deposited on the porous surface 24 of rotaryfilter 14.

For example, FIG. 11 provides a schematic illustration of a system withthree different nanomaterials, each contained in a separate reservoir147, 148, 149. Each of the reservoirs are fluidically coupled with arespective pump 137, 138, 139 that pumps a respective one of thenanomaterial suspension to a sonicating mixer 127, 128, 129. Thesonicating mixer may be programmable to manage the amount ofagglomeration and deagglomeration that occurs within the mixer. Also,additional additives may be added to the reservoir and/or the mixer tocontrol agglomeration/deagglomeration, for example. Each mixer isfluidically coupled with a distribution hub or splitter 117, 118, 119,which is schematically shown in one input channel being split into threeoutput channels in the example of a first splitter 117. In one example,a splitter 117, 118, 119 may be a single hub or a series of splittersthat split the nanomaterial suspension into a plurality of lines thatfeed individual ports 28 in the apparatus 10. An effluent that passesthrough the rotary filter 14 may be drawn by an effluent pump from theapparatus 10 to one or more effluent containers 115, for example.

In one example, such as illustrated schematically in FIG. 12, a singleline may be directed to one or more ports 28. Alternatively, as shown inFIG. 13, two lines, such as two lines that may contain two differentnanomaterial suspensions may be combined via a mixing hub or valve intoone or more inlet ports 28. In yet another alternative, such as shown inFIG. 14, three lines that may contain three different materials, such asthree different nanomaterial suspensions, and may be combined via amixing hub(s) and/or valve(s) into one or more ports 28. Any combinationof splitters and mixing valves may be combined to direct suspension toone or more ports 28. In one example, the splitters and mixing valvesmay be controlled, such as by switches, to turn on and off or switchcertain ports, splitters, mixing valves and the like to control the flowof a variety of suspensions through lines feeding one or more inletports 28. For example, programmable valves may be operated by a computerinterface or the like, as illustrated, schematically in the drawings. Inthe example of FIG. 15, a line 100 is fluidically coupled to an inletport 28, for example, such that a suspension passing through the line100 is transferred through the barrier 18 at the inlet port 28 and tothe porous surface 24 of the rotary filter. Each inlet port 28 may becoupled to an individual line 100 by any conventional connector, asshown in FIG. 15, for example, or may be connected to a plurality ofinlet ports 28 by an inlet hub or splitter disposed within the apparatus10. For example, a simple splitter is shown, schematically, in FIG. 16.The splitter or hub may be disposed nearer to the barrier 18 than isobvious in the schematic of FIG. 11. Indeed, the barrier may incorporateone or more splitters or expanders. In the simplified example of FIG.16, a single line 100 is split between two inlet ports 28 adjacent tothe barrier 18. To reduce inevitable confusion, the plurality of lines100 and inlet ports 28 are represented, schematically, in FIGS. 1, 3,and 5-6 as circles; however, any of a variety of couplings may be usedto connect lines 100 with inlet ports 28, as is known in the art.However, the arrangement of the plurality of ports 28 for deposition ofone or more nanomaterial suspensions on a rotary filter is not known andis not obvious. In one example, the fluid couplings are arranged inadvance within a particular apparatus 10 in order to produce a singletype of nanomaterial mat. In an alternative example, the distribution ofnanomaterial suspensions is programmable using valves and switches todirect nanomaterial suspensions to one or more ports. For example,distribution hubs 117, 118, 119 are illustrated, schematically, as beingwirelessly coupled to a laptop computer system 101 for controllingon/off and switching valves of the distribution hubs. In one example,each of the hubs/mixing valves or mixing inlets may be controlledwirelessly or by a wired connection via a computer processor or thelike.

FIGS. 7-9 illustrate examples of systems for continuous production ofnanomaterial mats. In the example of FIG. 7, the apparatus 10 isintegrated into a roll-to-roll system for continuous nanomaterialpapermaking. The schematic shows various zones of suction pressure (i.e.arrows pointing inward toward the center of a wheel) and releasepressure (i.e. arrows pointing outward toward the circumference of awheel). For example, suction pressure region 72 draws fluid introducedinto volume 71 from inlet ports 28 (best shown in FIG. 1) through therotary filter 14, depositing nanomaterials on the porous surface 24 ofthe rotary filter 14. For example, the rotary filter may utilize apolyethylene teraphthalic ester membrane or a polycarbonate track etchmembrane, which is permeable to the carrier fluid but retains thenanomaterials on its surface. One or more neutral regions 73, which maybe provided by a block 11, as best illustrated in FIG. 1, for example,has no pressure differential. Reverse pressure region 74 applies arelease pressure to the mat to help peel the mat from the surface 24 ofthe rotary filter 14. In this example, the peeling roller 17, which isrotating clockwise (cw) has both a suction pressure region 82 forpeeling the mat 75 from the surface 24 of the rotary filter 14 and areverse pressure region 84 for assisting in transfer of the mat 75 tothe transfer roller 87, which rotates counter clockwise (ccw). Thetransfer roller 87 has a suction pressure region 85. Since a transferfilm 78 is supplied by a transfer film roller 70, which is rotatingclockwise (cw), no reverse pressure region is needed for the transferroller 87. FIG. 7 shows that the transfer film 78 and nanopaper 75 aredirected to a reel 80, which rotates counter clockwise (ccw) fortransport or subsequent processing, for example.

In an alternative example, as shown in FIG. 8, a peeling roller 17 has asingle suction pressure zone 82. The mat is omitted from FIGS. 8 and 9for clarity. A belt 89, such as a porous polytetraethylene teraphalatebelt, may be used to transfer the mat (not shown) to a transfer roller87, which has a single reverse pressure region 85, which helps to peelthe mat 75 and transfer film 78 from the belt 89. This transfer roller87 may be the same as the transfer roller 87 illustrated in FIG. 7, forexample; however, in this example, the transfer roller 87 rotatesclockwise (cw) and is disposed on an opposite face of the transfer film78, for example. While the belt 89 adds a component that may be subjectto wear and tear, over time, the system illustrated in FIG. 8 may bepreferable to the system in FIG. 7, because the peeling roller 17 may besimplified by having only a single suction zone.

In yet another example, as illustrated in FIG. 9, for example, amulti-step process is shown. The mat 75 produced during operation of thefirst apparatus 10 is transferred to a second apparatus 90 for furtherprocessing, such as adding another layer of nanomaterial, consolidatingand/or binding the mat or otherwise functionalizing the mat. In thisexample, a belt 89 connects a first peeling roller 17 and a transferroller 91, and the first peeling roller has only a single suctionpressure zone 82. The transfer roller 91 has a single reverse pressurezone 92 for transferring the mat 75 to the second rotary filter of thesecond apparatus 90. Then, any type of fluid or gas may be passedthrough the mat 75 for further processing of the mat 75 in one or moresubsequent processing steps. A plurality of process steps may becombined by chaining two, three or even more rotary filters using thisconfiguration. However, in this example, a peeling roller 97 is shownthat functions similarly to the peeling roller 17 in the example of FIG.7. The mat 75 is then peeled by this second peeling roller 97 thatcomprises a suction pressure zone 96 that works with reverse pressurezone 93 of the second apparatus 90 and a reverse pressure zone 95, whichworks with a suction pressure zone 85 of a second transfer roller 87 toapply a transfer film 78 to the mat 75. The transfer film 78 and mat 75are then directed to a reel 80 by a transfer roller 87, which may or maynot have a suction zone 85, as previously shown. The reel 80 may be usedfor transport or further processing, for example.

As illustrated schematically in FIG. 10, each inlet port 28, whichprovides an orifice passing completely through the barrier 18, may befluidically coupled, such as by a tube and couplings, to one of aplurality of pumps 137 by a distribution hub 117, which directs asuspension containing nanomaterials directly to each inlet port 28 by aplurality of tubes or “lines” 100, as referred to herein, for example,from one or more suspension sources 147, 148, 149, such as reservoirscontaining nanomaterial suspensions. In one example, a reservoirdistribution system 147 includes a sonicator 127 for disbursingnanomaterials within the suspension and for controlling agglomeration.For example, when lines 100 are utilized, the volume external to thebarrier 18 may be a void (devoid of any suspensions, but not necessarilya vacuum, i.e. the void may contain air or other gases or even a liquid.Lines 100, which may be tubes, such as flexible polymer tubes, maydeliver a suspension fluid to each inlet port 28 or selected inletports. For example, each inlet port 28 may be supplied a differentsuspension mixture or ports may be grouped together to provide differentnanomaterials and additives through the thickness of a mat asillustrated in the simplified schematic of FIG. 17, which illustratesthree distinct layers 297, 298, 299 from the three zones of inlets 287(high contrast fibers), 288 (grayed) and 289 (low contrast fibers). FIG.18 illustrates inlet ports 28 grouped by zones. For example, the firstzone 287 may comprise nanomaterials and a release agent, the second zone288 may comprise the same or different nanomaterials and a bindingagent, and the third zone 289 may comprise the same or differentnanomaterials and a coloring agent and/or an adhering agent, such as atacky substance or adhesive.

Alternatively, changes to the composition may gradually change throughthe thickness of the mat, rather than being divided into discreetlayers, merely by selecting the distribution of lines to ports 28, asillustrated schematically by the dotted shading of FIG. 19. In FIG. 19,the dots are meant to represent an additive that has a gradient throughthe thickness T of the first mat layer (i.e. nearest the filtermembrane). For example, a higher concentration of release agent may bepresent at the surface between the mat and the filter membrane to helpwith peeling of the mat from the membrane. In addition, thisconcentration may be greater at startup than later, after the mat ispeeled initially. However, the illustration is not limited to this oneexample. There are many reasons for desiring an concentration gradientof one constituent in another through a thickness or along a length ofmat.

In one example, as illustrated schematically in FIG. 19, a compositionof a first portion of a continuous mat is selected by directingnanomaterials and additives through only a fraction of the ports at thestart of the process. Then, the composition of the mat is changed byadding nanomaterials and/or additives from other sources having adifferent selection of nanomaterials and additives. For example, thefirst portion of the mat may have a release agent added, and a laterportion of the mat may reduce or eliminate the release agent from thesuspensions being directed to the filter. By including a release agentonly in the first zone 287 of FIG. 18, a surface layer with a higherconcentration of release agent will be produced. By controlling theamount of the additive mixed in the mixing valve, a particularconcentration gradient of an additive may be obtained, for example.

For example, the schematic representation in FIG. 11 shows threedifferent nanomaterial suspensions 147, 148, 149, coming through threedifferent sonicators 127, 128, 129 and three different pumps 137, 138,139, flowing to three different hubs (splitters and/or mixing valves)117, 118, 119, from which one or more fluid lines are shown carryingnanomaterial-containing suspensions to respective inlet ports 28. Forexample, a bottom portion of the mat (closest to the filter membrane inthe cross section of FIG. 19) may comprise nanotubes and a releaseagent, wherein the release agent is concentrated at the surface incontact with the filter membrane and a gradient in the concentration ofthe release agent extends only a short distance into the surface of themat. A top portion may be comprises of an entirely different suspensionor combination of suspensions, such as a cellulose material, which maybe colored any color or white. By utilizing the mixing valves and inletports 28, any number of additives may be added in layers or gradientsthrough a thickness of a mat or along the length of a mat or in anypattern along the mat. For example, a mat may comprise a printed circuitboard, or the like, by controlling the layering and location ofmaterials supplied through each of the ports 28.

In one example, as illustrated in the schematic detail of FIG. 20, eachinlet port 28 may be multiplexed and/or connected by a valve 366, whichmay be a mixing valve, that determine the origin(s) of materialsdirected through inlets 28 connected to the valve by a fluiddistribution line 100. Thus, the composition through each inlet 28 maybe turned on or off and may be changed over time, as materials aredirected through each port. By controlling the valves 366, each of theports 28 provide a capability of making three dimensionally structurednanomaterial mats, as illustrated schematically in FIG. 17. FIG. 20provides an example of a mixing valve with three lines in 361, 365, 363and three sources 360, 362, 364. The valve body 366 is capable ofcontrolling the fluid out line to an inlet 28 to mix any proportion ofthe three sources or to turn off and on any or all of the sources. Thisprovides for control of concentration of suspensions and additives atone or more inlets 28 or zones. A combination of mixing valves, on-offvalves and splitters may be used. Preferably, a mixing valve is acompact valve body that can be placed adjacent to the barrier/inlets.FIG. 17 schematically illustrates a volume of mat divided into layers,rows and zones. The lines between zones are added only to show the zonesmore clearly, as there may be a gradient between one zone and the next.The gradient may be a sharp gradient or a gradual gradient, depending onprocessing speed and conditions. In this simplified example, only tworows a,b are shown. Alternatively, a plurality of rows may be providedby the inlet ports 28, such as the four rows shown in FIG. 21.

The simplified example of FIG. 17 shows a volume of mat having threelayers 297, 298, 299, two rows (a,b) and three zones along the length ofthe mat from 220,221 to 224,225. A first layer 297 has a first row (a)with a different composition than a second row (b). A second layer 298shows a gradient from dark to light, which represents a concentrationgradient within the second layer 298. The third layer 299 has threedifferent zones along the length of the layer. The last zone 224,225 isrepresented by cross hatching and has a different composition than theother two zones. The second zone 222,223 is shown to have a lightercontrast showing that it has a lower concentration of one of itsconstituent elements. The first zone 220,221, in contrast, has a darkershade of fibers showing that it has a higher concentration of one of itsconstituents. While each of the three layers shows a differentvariation, the variations may be mixed and matched in any of the layersby controlling the valves and the inlet zones connected to the valves.Any number of layers may be provided, and the length of zones may beadjusted, as needed, to provide a desired structure. The ultimateresolution of the three dimensionally structured mat depends on thespeed of the valves, the size of the zones and the length and volume ofthe lines 100 connecting the valves to the inlet ports 28, for example.

FIG. 21 shows an example of a zone having a plurality of inlets 28. Theview is of the inside surface of the barrier 18, with other surfaces cutaway. Each of the inlets 28 is shaped to distribute the suspension overa particular row and for a particular distance. This type ofdistribution structure for the purpose of claim limitations is referredto as a “row and zone inlet” as the structure of each inlet is shaped todistribute suspension passing through the inlet only to a particularregion on a surface 24 of the rotary filter 14 (or upon a mat ofmaterials previously deposited thereon). A particular region maycomprise a zone or a portion of a zone of any shape and size limitedonly to the confines of the gap between the barrier 18 and the surface24. A row of a particular composition may be as short as a zone or aslong as a continuous mat, and the length may be controlled by operationof a valve or valves. A width of a row of a particular composition iscontrolled by the dispersion of the suspension from an inlet or inlets.For example, a concave surface of the rows shown in FIG. 21 assist inlimiting the dispersion of suspension from each of the inlets shown. Across section of the concave surfaces of the zones shown in aperspective view in FIG. 21 are schematically represented in FIG. 18,and these zones, for example, provide the control needed, in conjunctionwith hubs (splitters and valves), for making mats with the types ofstructures shown in FIG. 17, for example.

This detailed description provides examples including features andelements of the claims for the purpose of enabling a person havingordinary skill in the art to make and use the inventions recited in theclaims. However, these examples are not intended to limit the scope ofthe claims, directly. Instead, the examples provide features andelements of the claims that, having been disclosed in thesedescriptions, claims and drawings, may be altered and combined in waysthat are known in the art.

1. A mat of material in the form of a sheet or ribbon, the matcomprising: a plurality of layers, wherein each of the layers is formedfrom a composition of nanomaterials disposed locally at specificlocations within each of the plurality of layers, and the composition ofnanomaterials is selected from a particular source or sources ofnanomaterials suspended in a working fluid that are deposited at thespecific locations, such that the composition of nanomaterials depositedlocally at the specific locations comprises exfoliated graphene,graphene oxide platelets, single-walled and multi-walled nanotubes,nanofibers, micro-fibrillated cellulose, nano-fibrillated cellulose,nanocrystalline cellulose, metal particles, quantum dots, ceramicparticles, biomaterial particles, chitins, such as chitosan, nanowires,such as silicon, carbon, germanium and other nanowires, nanoclays, suchas montmorillonite, bentonite, kaolinite, hectorite and halloysite,proteins, enzymes, antibodies, cellular materials, hemoglobin, DNA, RNA,liposomes, ribosomes, viruses, bacteria, marking and tagging agents orcombinations of any of these; at least a portion of the working fluid isseparated from the composition of nanomaterials with at least a portionof the composition of nanomaterials being deposited at the specificlocations; and each of the plurality of layers has a differentcomposition than other layers of the plurality of layers at the specificlocations within each of the plurality of layers.
 2. The mat of claim 1,wherein the working fluid comprises binders, surfactants, solvents,monomers or polymers.
 3. The mat of claim 2, wherein a portion of theworking fluid remains within the composition of nanomaterials depositedlocally at specific locations within each of the layers.
 4. The mat ofclaim 1, wherein the composition of nanomaterials deposited locally atthe specific locations comprises nanotubes.
 5. The mat of claim 4,wherein the nanotubes are comprised of carbon, boron, molybdenum,borides, nitrides, carbides, or combinations of carbon, boron,molybdenum, borides, nitrides or carbides.
 6. The mat of claim 5,wherein the nanotubes are comprised or carbon.
 7. The mat of claim 6,wherein the nanotubes are single-walled carbon nanotubes.
 8. A devicefor making the mat of claim 1, comprising: a porous substrate mountedsuch that the porous substrate is translatable; a pressure gradientregion, wherein the porous substrate translates through the pressuregradient region such that a first pressure is present on a first side ofthe porous substrate and a second pressure is present on a second sideof the porous substrate, the first pressure being greater than thesecond pressure; a plurality of outlets disposed in relation to thepressure gradient region such that a liquid suspension comprising aworking fluid and a composition of nanomaterials comprised of exfoliatedgraphene, graphene oxide platelets, single-walled and multi-wallednanotubes, nanofibers, micro-fibrillated cellulose, nano-fibrillatedcellulose, nanocrystalline cellulose, metal particles, quantum dots,ceramic particles, biomaterial particles, chitins, such as chitosan,nanowires, such as silicon, carbon, germanium and other nanowires,nanoclays, such as montmorillonite, bentonite, kaolinite, hectorite andhalloysite, proteins, enzymes, antibodies, cellular materials,hemoglobin, DNA, RNA, liposomes, ribosomes, viruses, bacteria, markingand tagging agents or combinations of any of these that is dispensedfrom one or more of the plurality of outlets is deposited on the poroussubstrate, such that at least a portion of the working fluid is drawnthrough the porous substrate and separated from the composition ofnanomaterials; a control system, wherein the control system is coupled,fluidically, to the plurality of outlets such that the composition ofnanomaterials at each of the plurality of outlets is selectivelydispensed from the one or more of the plurality of outlets and separatedfrom the working fluid to form a layer of a plurality of layers of themat, each layer having a composition of nanomaterials selectivelydeposited at specific locations within the layer by the plurality ofoutlets, such that the composition of nanomaterials in the layer isdifferent than the composition of nanomaterials of the other layers ofthe plurality of layers of the mat.
 9. The device of claim 8, furthercomprising a release region comprising a third pressure on the firstside of the porous substrate and a fourth pressure on the second side ofthe porous substrate, wherein the third pressure is less than the fourthpressure, wherein when the porous substrate translates through therelease region, the mat is released from porous substrate.
 10. Thedevice of claim 8, wherein the porous substrate is a rotary filter. 11.The device of claim 10, further comprising a release region comprising athird pressure on the first side of the porous substrate and a fourthpressure on the second side of the porous substrate, wherein the thirdpressure is less than the fourth pressure, wherein when the poroussubstrate translates through the release region, the mat is releasedfrom porous substrate.
 12. The device of claim 11, further comprising ashield region, wherein the shield region separates the pressure gradientregion from the release region, and the shield region reduces anypressure differential within the shield region.
 13. The device of claim12, further comprising a peeling roller, wherein the peeling roller isdisposed adjacent to the release region and is provided such that thepeeling roller provides a pressure differential along an arcuate surfaceof the peeling roller, which provides a suction pressure opposing thefirst side of the porous substrate, and the pressure differential alongthe arcuate surface of the peeling roller draws the mat onto the peelingroller.
 14. The device of claim 13, wherein the peeling roller hasanother arcuate region where the pressure differential is reversed,separating the mat from the arcuate surface of the peeling roller. 15.The device of claim 14, further comprising a transfer roller arranged toapply a transfer film onto an exposed surface of the mat as the mat isin contact with the peeling roller.
 16. The device of claim 14, furthercomprising another porous substrate, wherein the mat is separated fromthe porous substrate by the peeling roller and is directed to theanother porous substrate, and the second porous substrate is arranged inanother pressure gradient region, wherein the another porous substratetranslates through the another pressure gradient region such thatanother fluid passes through the mat.
 17. The device of claim 16,wherein the another fluid comprises another liquid suspension depositedby another plurality of outlets, such that the another layer iscomprised of another composition of nanomaterials, different from thecomposition of nanomaterials in the layer selectively deposited atspecific locations as recited in claim
 8. 18. The device of claim 10,wherein the rotary filter is comprised a porous polymer membrane. 19.The device of claim 10, wherein the rotary filter is comprised of astructural mesh with a porous polymer membrane supported by the mesh.20. The device of claim 19, wherein the mesh is a metal mesh.
 21. Thedevice of claim 10, wherein the rotary filter rotates about a centralaxis, translating the rotary filter past the pressure gradient region,and further comprising rotary seals sealing the sides of the rotaryfilter such that the working fluid passes through, and not around, therotary, when the rotary filter is disposed within the pressure gradientregion.
 22. The device of claim 21, further comprising a mechanicaldrive arranged such that the mechanical drive rotates the rotary filter,translating the rotary filter through the pressure gradient region. 23.A method of making a sheet having a plurality of layers using the deviceof claim 8, the method comprising: disposing a porous substrate within apressure gradient; controlling the composition of a liquid suspension,such that the composition of the liquid suspension comprises a workingfluid and a composition of nanomaterials comprised of exfoliatedgraphene, graphene oxide platelets, single-walled and multi-wallednanotubes, nanofibers, micro-fibrillated cellulose, nano-fibrillatedcellulose, nanocrystalline cellulose, metal particles, quantum dots,ceramic particles, biomaterial particles, chitins, such as chitosan,nanowires, such as silicon, carbon, germanium and other nanowires,nanoclays, such as montmorillonite, bentonite, kaolinite, hectorite andhalloysite, proteins, enzymes, antibodies, cellular materials,hemoglobin, DNA, RNA, liposomes, ribosomes, viruses, bacteria, markingand tagging agents or combinations of any of these; depositing theliquid suspension on the porous substrate at a specific location,locally, on the porous substrate; drawing the liquid suspension throughthe porous substrate depositing the composition of nanomaterials,locally, at the specific location; repeating the steps of controlling,depositing and drawing at a plurality of the specific locations,locally, on the porous substrate such that a plurality layers of thesheet are formed, and each of the plurality of layers has a selectivelydifferent composition than other layers of the plurality of layers atspecific locations within each of the plurality of layers.